Sprint’s Spark LTE network disables data when handling calls

With a promise of 50-60Mbps speeds, Sprint's new Spark network looks to maximize data performance while bringing HD Voice to tri-band smartphones like the Galaxy S4 and S5 and the HTC One M8. So far, the Spark switch has been flipped in limited markets like Seattle, San Francisco, and New York, providing enough data for Consumer Reports to file a report on the network's biggest asterisk thus far.

In tests, Consumer Reports has confirmed that phones connected to Sprint's Spark network cannot access any over-the-air data services when in the middle of a phone call. That differs from many of the company's current 4G LTE smartphones, which come equipped with a separate LTE antenna that lets you send and receive data while using Sprint's CDMA network for voice calls. (However, Sprint's iPhone 5 launched without support for simultaneous voice and data use.)

Sprint offered a statement to Consumer Reports confirming the issue, stating, "Simultaneous voice and data sessions are not available on tri-band devices unless the customer is using WiFi." That may be cold comfort to stranded smartphone addicts who have become accustomed to juggling calls, maps, and Web searches, but at the very least, their resulting reduced data use may be less likely to be hit by data throttling.

This week, Sprint and Virgin Mobile customers began receiving text message warnings about throttling for "the top 5 percent" of data users. The change in Sprint policy, announced in March, will go into effect on June 1st, according to the texts; a FAQ at Sprint's site estimates that such throttling will most likely affect users who go over 5GB of data use per month. It's a break from Sprint's consistent advertising about unlimited data, and it will leave the telco with one less selling point to lordoverrivals.